Go Kart Newbie - Clutch Question

[Kristajoy15]

I bought a go kart from my neighbor with the intention to replace the clutch and get it going for my kids. I have a new Predator 212 engine, but the clutch replacement I bought doesn’t lock onto the crank shaft (and hopefully I’m accurate in my description). The old clutch had a keyway that could be locked but the replacement I got doesn’t, so it slides.
Again, I’m a newbie so I’m not sure what to do. I also can’t seem to find shaft collars to help with the issue. First picture is the old clutch and key and second is the replacement that slides. Help!

 

[Master Hack]

First picture is the old clutch and key and second is the replacement that slides. Help!

What do you mean "it slides"?
Slides along the length of the crankshaft?
You can spin it without spinnibg the shaft?
Second pic shows the clutch has a key built in. If it doesn't engage the keyway in the shaft then it must betoo big.

 

[panchothedog]

The old clutch was slotted so you insert a removable key to lock them together. The new clutch has the key built into it. Very common. Is your new one the correct diameter for the engine shaft? I can't understand how this is giving you trouble.

 

[Master Hack]

but the clutch replacement I bought doesn’t lock onto the crank shaft (and hopefully I’m accurate in my description). The old clutch had a keyway that could be locked but the replacement I got doesn’t, so it slides

Are you forgetting the bolt that "locks it down"?
maybe a dumb question, but this is pretty simple. I'm having difficulty understanding the problem.

 

[Edwin Spangler]

Looks like the Max torque is the new clutch, with cut out keyway

Old clutch had the key built into the clutch?

With max torque clutch, it just spins? Sounds like you need a bigger key if im accurate here.

 

[Hellion]

What's wrong with the old clutch? Roasted, toasted to death and no longer works? Keep the old one because it's a Max Torque brand and you can probably buy new clutch shoes and springs for it.
A centrifugal clutch can and will last for years provided that they are used correctly and operated at full engagement. Here's some pointers on their proper usage...

10 Things to Know about a Centrifugal Clutch​

https://www.bmikarts.com/10-things-about-centrifugal-clutch

In case you need the bolt on the end of the crankshaft (that prevents the clutch from sliding off the shaft) it is a 5/16″-24 bolt, which is a fine threaded bolt with 24 threads per inch. Use a lock washer against the bolt and place a larger flat washer against the clutch.

Looks like the Max torque is the new clutch, with cut out keyway

Reading comprehension is not your strong suit.

 

[Hellion]

If there is a lot of extra longitudinal play on the shaft and the clutch is sliding to and fro on it, you can use washers with the proper inside diameter (ID) to take up the space on the shaft.

Also: consider running the clutch reversed on the shaft; that is. with the sprocket side facing the engine -- the clutch will work either way, it doesn't care, but it's technically safer for your kids because the "business end" is on the inside. Of course doing this may mean the chain will no longer align with axle sprocket, so you may need to move the axle sprocket over (which may be easier said than done). Just detailing some options for you. On the issue of clutch safety, also consider using a clutch guard for it and no long hair hanging over the back of the seat!

 

[Edwin Spangler]

Reading comprehension is not your strong suit.

Thought maybe he mistook which picture was first.. Are you saying my statement is incorrect?

 

[Master Hack]

Have we resolved the key situation?

just to be clear the new clutch has a nolosem key (no lose 'em)
meet the new key, same as the old key.

 

[JimD]

You got the key cut it to 3/4" long and put a slight ramp on the key to match the one on the crankshaft. Doesn't have to be perfect just trying to get the maximum length key as possible. You will need to go buy a 5/16-24 hex bolt 3/4" long and a flat washer 1" diameter 5/16 bore and a lock washer to hold the clutch on.

 

[Kristajoy15]

You got the key cut it to 3/4" long and put a slight ramp on the key to match the one on the crankshaft. Doesn't have to be perfect just trying to get the maximum length key as possible. You will need to go buy a 5/16-24 hex bolt 3/4" long and a flat washer 1" diameter 5/16 bore and a lock washer to hold the clutch on.

I wasn’t sure if this was something I could do, but it makes total sense!

 

[Kristajoy15]

Have we resolved the key situation?

just to be clear the new clutch has a nolosem key (no lose 'em)
meet the new key, same as the old key.

View attachment 151857

Ah, gotcha. And that makes sense…but again, I’m new to this. So is it common to have to add in

What do you mean "it slides"?
Slides along the length of the crankshaft?
You can spin it without spinnibg the shaft?
Second pic shows the clutch has a key built in. If it doesn't engage the keyway in the shaft then it must betoo big.

slides as in, once I’ve got the clutch on the crankshaft and chained, the actual clutch slides along the diameter of the crankshaft. The old crankshaft + clutch had the removable key and could lock in place, but obviously not this one so it’s moving around

 

[Master Hack]

the actual clutch slides along the diameter of the crankshaft

I'm sorry but your description doesnt make sense. There's only two ways it can move.
1. The diameter of the clutch is wrong for the crankshaft. That would be real obvious.
2. The "thickness" of the clutch is less than the length of the crankshaft. The clutch would slide back and forth along the lengh of the crank. Shims and/or sleeves would take upthe excess space. That and some key stock and yer good.

 

[Hellion]

The fixed/immobile key in the bore of the new clutch looks narrower to me, than the width of the keyway on the engine. Maybe it's an optical illusion because of perspective/camera focal length, but if I'm right, the clutch may be wobbly on the shaft on the axis of rotation or direction "B" on my illustration...



I think the rest of the discussion has been about slop or looseness on the shaft in the A direction.

 

[Master Hack]

I'm picturing the "C" direction, where the doughnut thingy on the left moves toward and away from the viewer. I don't think "slides" describes anything else. it is not clear (at least to me) what he means. I can be purdy dense....

 

[Kristajoy15]

I'm sorry but your description doesnt make sense. There's only two ways it can move.
1. The diameter of the clutch is wrong for the crankshaft. That would be real obvious.
2. The "thickness" of the clutch is less than the length of the crankshaft. The clutch would slide back and forth along the lengh of the crank. Shims and/or sleeves would take upthe excess space. That and some key stock and yer good.

So sorry, multitasking doesn’t help to explain things clearly in text!

The old engine on this cart was toast, but I’m starting to wonder if the old clutch was still okay. I have a new predator engine now

I'm sorry but your description doesnt make sense. There's only two ways it can move.
1. The diameter of the clutch is wrong for the crankshaft. That would be real obvious.
2. The "thickness" of the clutch is less than the length of the crankshaft. The clutch would slide back and forth along the lengh of the crank. Shims and/or sleeves would take upthe excess space. That and some key stock and yer good.

I believe that shims or sleeves will help solve the movement issue. I just need to find them lol. I’m starting to think the old clutch still works and the old engine was the problem. I just have a lot more to learn. Thank you!

 

[Karttekk]

Does your clutch happen to have set screws machined into it? Use those to lock it onto the crankshaft if an option. Maybe find something like these that slide over the crankshaft key as spacers. Kinda pricey though.

Pardon Our Interruption

 

[JimD]

Never use set screws unless the crankshaft isn't drilled and tapped. You always want to hold the clutch in place with a bolt and washer so it has the ability to try and self align with the rear sprocket which never runs true to start with. Drill and tap the hole yourself if it is an American 4 cycle engine. Not that hard to do.

 

[Karttekk]

Jim, I realize the clutch needs bolted to the crankshaft. What I meant was if there were set screws machined into the clutch, tightening those could keep the clutch from sliding in and out on the crankshaft if I understood him right. I would never trust set screws as the only way to secure a clutch, it would fly off within seconds more than likely. Appreciate the reply though. Thanks.

 

[JimD]

The donut on our clutches tells you NOT to use the set screws. Hold the clutch on with a bolt and washer. The only time to use a set screw is when the crankshaft doesn't have a drilled and tapped hole. You won't want to use set screw if you can hold the clutch in place with a bolt and washer. Set screw will mar the crankshaft making it harder to slide a clutch on or off. The clutch needs to float on the crank to stay aligned with the rear sprocket since they don't run true.